1. we are given :
• that the mass fraction of Na2CO3 = 2%
meaning 2 grams of Na2Co3 was dissolved in 98g of water .
∴ total mass of solution = 100g
• Density = 1.019g/mL.
,
• Molar mass Na2CO3=105,9888 g/mol
2. Calculate volume
Density = mass /volume
∴Volume = mass/density = 100g /1.019g/mL.
= 90.66mL.
3.Calculate moles of the solution
n = mass Na2CO3/MolMass Na2Co3
= 2 g /105.9888g/mol
∴moles of Na2CO3 =0.019moles Na2CO3
4. Calculate the Molarity (concentration)of the solution
Molarity =( n/v) * 1000
= (0.019mol/(90.66/1000) L
= (0.019/90.66)*1000 ( multiply by 1000: 90.66/1000=0.09066)
=0.21M
This means that the concentration of the solution is 0.21M